Problem in Public key cryptography

Question

I have a problem in PKC

Consider the following scenario

when a sender needs to send a message to the receiver :

• sender generate the cipher text Using the receiver's Public Key
• receiver Use receivers private key to decrypt the cipher text.

So my problem is sender is not generating any keys ? and how the Public key of receiver send to sender ?

Answer 1

Correct, the sender does not need to have any encryption keys of its own - it only needs the public key of the receiver to encrypt a message that only the receiver can decrypt.

The receiver's public key can be distributed openly and publically. There is no need to protect it, since the only thing it can be used for is to encrypt data that only the receiver can decrypt. In S/MIME email encryption, for example, it's common to attach your public key to every cleartext email you send so that anyone you correspond with can encrypt email they send to you using your public key.

Note that when the receiver decrypts a message encrypted with their public key, they have no idea who created the data found in the message. A digital certificate of the sender cryptographically signed by a third party trusted by both receiver and sender could be added to the encrypted message to provide proof of origin to the receiver.